Suppressors for firearms, also known as silencers, generally operate to reduce the audible noise or sharp report of a firing weapon by means of reducing and controlling the energy level of attendant propellant gases. Generally the techniques employed utilize a series of baffles which control and delay the flow, expansion and exiting of propellant gases; forcing the propellant gases to pass through various temperature absorbent materials; or a combination of these or functionally similar techniques to reduce the temperature and abrupt discharge of propellant gases. The result achieved is a corresponding reduction in the noise produced by the exiting propellant gases.
Most suppressors employ directly, with a variant, or in combination the basic techniques aforementioned to accomplish the desired function and result, and devices of such construction largely comprise the prior art. In most cases involving baffles or a variant such as helical wound screws or chambers which deflect and channel gas flow, relatively precise and costly fabrication and assembly is required. Accurate alignment and narrow tolerances required to effectively deflect propellant gases usually necessitate that metal baffles, most often circular and flat or conical in shape, be fabricated by costly machining or special forming dies. In most cases employing primarily the use of temperature absorbent materials, accumulation of spent residue from repeated firing can reduce efficiency and require cleaning or replacement of components. The metal mesh or other absorbent material can be degraded structurally by the effect of blast and heat, and become so clogged by powder residues as to severely limit gas and thermal absorptive capabilities. In the cases of suppressors employing nonpermeable rubber or other elastomer materials as baffles or "wipes" through which the projectile actually passes during firing, repeated firings cause gradual physical destruction of the baffles or "wipes" and reduced effectiveness.
Another technique requires the drilling of gas venting holes or ports either in the barrel of the firearm which becomes integral to the suppressor assembly, or the inclusion of a barrel extension or similar within the suppressor itself which is so drilled to vent propellant gases into the suppressor and slow projectile velocity to a subsonic level, reducing both blast and sonic noise generated by modern high velocity ammunition. Such devices may also employ a combination of the aforementioned techniques to further aid reduction of noise. Where such devices are made integral to a firearm the suppressor is usually limited to use on a single firearm. Where the firearm barrel is modified through drilling, the firearm itself is rendered unsuitable for practical use without the integral suppressor in place.